Updated 17 Aug 2016

Powertech

Rechargeable 2500 (green) SB-1738

Bottom line: The Powertech Rechargeable 2500 (green) SB-1738 has very good battery life per use and OK long-term endurance.

Rechargeable 2500 (green) SB-1738
Consumer score
72
Avg price

$6.23

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Test results

Overall score
Good
72
Battery life
Very good
8.1/10
Long term endurance
OK
5.8/10
Charge retention
Good
7.5/10
Ruggedness
Good
7.0/10

Good points

  • Very good battery life per use.
  • OK long-term endurance.
  • Good charge retention.
  • Rugged construction.

But

(No obvious bad points.)

How we test

We place the batteries in a computer-controlled test rig that charges them, then discharges them at a rate equivalent to the demand of a high-drain device — like a remote-controlled car. Once the cell voltage reaches 1.0V, equivalent to empty for most power-hungry devices, the rig charges them again.

  • We judge each battery’s long term endurance by measuring how many cycles until its capacity falls to half its initial value.
  • The battery’s average capacity over the amount of charge/discharge cycles before failure gives our battery life per use score.
  • Rechargeable batteries gradually lose charge while sitting idle. We measured this rate of “self-discharge” for each battery to get our charge retention in storage score.
  • We also look at the ruggedness of each battery’s construction by placing them in a rotating cylinder (a bit like a gentle tumble-dryer) for 24 hours, before taking them out and sorting them from least to most damaged.

Key data

Product

Avg price
$6.23

Specifications

Type
NiMH
Cycles to failure
99
Total lifetime capacity (mAh)
213000
Measured initial capacity (mAh)
2343
Average capacity (mAh)
2001
Average discharge time (min)
102
Annual charge loss in storage (%)
40